Who would you like to see as an Avenger who has never been one?

[Photon Torme]

....Iceman.
Songbird
Johny Storm
Monet
Micromax
Cyclops(Pre Emma)
Jean Grey
Nightcrawler
Morph
Nocturne.

[Darth Phoenix]

He can lead a Dark Avengers, or an Antihero/antivillain Revengers team.

Doom leader
Blade
Magik
Moondragon
Aries
Namor

some of these Avengers and X might make that type of team

[EmperorDoom]

Exactly, sadly he isn't written that way these days.

Pretty much.

[Project Initiative Cascada]

I'd like to see Emma Frost as an avenger, she has the perfect power set for it and her ruthlessness would create conflict and get shit done. She'd be perfect.

Agreed. She would make a remarkable Avenger with her powerset and prowess. I don't see her joining in any lifetime though, even if she was personally invited.

I also think Black Cat, Rachel Summers, Magik, X-23, Songbird, Blink, Nocturne, and Elektra will make great Avengers.